It was always a priority to us to figure out, 'How do we include Jack in this monumental day?' [of] Kate's wedding. She's so connected to her father and if ever she'd been feeling strongly linked to him, it would be around a wedding, when so many emotions come up. It felt really realistic to us that she'd be dreaming about him while she was wishing that she was there. It just felt like a very organic way to include him. And then even for us, when [Milo Ventimiglia] stepped on set, it was so surprisingly emotional to see him that age and also to see the way Rebecca reacted to him. It took all of our breaths away in a way that we didn't expect. It was so moving, and their performances were so beautiful. It was so exciting for us to get to use him in that way.

This Is Us did get Jack involved with Kate and Toby's wedding in other ways throughout the episode, such as Kate deciding to pour some of Jack's ashes on that tree, and how the wedding itself was interspersed with memorable moments withJack from Kate's childhood. So the writers technically didn't need to figure out a way to get a new look out of Milo Ventimiglia, but Kate's dream sequence definitely added further proof of just how emotionally devastating Jack's death continues to be in her life. (As someone whose father died years before my own wedding, I definitely understand how seemingly subdued feelings like that can rise to the surface during big life changes.)

Such a germane reasoning paid off, too, because it was indeed as poignant as television-ly possible to see present-day Rebecca getting to once again share smiles with the (former) love of her life. It would have been great had it happened in a grocery store parking lot, but setting it as a 40th anniversary vow-renewal was about as smart and thematically valid as anyone could have hoped for. It should have felt weird, considering Miguel is married to this Rebecca, but nope.

When speaking with TVLine, co-showrunner Elizabeth Berger remarked on Mandy Moore's work during the scene, praising the nuanced differences between this performance and her normal current era performances.

It was so interesting, to see [Mandy Moore] in those vow-renewal scenes, the way her body language changed and her face changed. You really felt like you were watching an entirely different woman than the woman we know, usually, in that time period. I thought it was just brilliant.

Sadly, This Is Us won't be giving us young, middle-aged or old versions of Jack in the near future, as the NBC hit won't be back in primetime until Season 3 hits next fall. Check out what co-star Jon Huertas told us about Miguel's future with Rebecca, and head to our midseason premiere schedule to see what'll be debuting and returning in the meantime.